Co sleeping

I started co sleeping with my son about 1 1/2 wks ago. I’m not asking for opinions about whether that’s the right or wrong thing to do. It’s the best thing we’ve found that works for our baby & if I can find a solution to this problem I’m having, we’ll keep doing it.

So when my husband has been awake, 2X now he’ll look over & notice my arm is up & over onto the baby’s face/body. I’m not suffocating him but it freaks him out so he wakes me to move. I don’t understand why I’m doing this cause I’m a really light sleeper since I’ve had him & have been very alert to mine & his movements. I was thinking maybe I’m a little more tired when I have done this and it’s why I don’t realize it..Anyone had this happen with them, what did you do?